Re: O->A loan

hi,
> yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi) wrote:
>> hi,
>>
>> i'd like to to either fix or remove O->A page loaning.
>>
>> the biggest problem is the lack of users. thus no way to test.
>> any ideas?
>
> After looking at O->A loaning code in yamt-pagecache branch, looking at
> the benchmark results by Jaime (some data was sent privately, I think)
> and contemplating about this mechanism - I tend to think that O->A loaning
> should be removed. It is a significant code complexity in UVM with some
> special casing and benchmarks indicate that the benefit is somewhat small.
>
> Does not seem to be worth, does it?
with this particular use alone, i tend to agree.
fwiw, the following is probably one of the best cases for loaned read.
YAMAMOTO Takashi
without loaned read:
kuma% dd if=/netbsd bs=1m|wc -c
14+1 records in
14+1 records out
14768691 bytes transferred in 0.038 secs (388649763 bytes/sec)
14768691
with loaned read:
kuma% dd if=/netbsd bs=1m|wc -c
14+1 records in
14+1 records out
14768691 bytes transferred in 0.023 secs (642117000 bytes/sec)
14768691
>
>>
>> YAMAMOTO Takashi
>
> --
> Mindaugas